Re: Capacitor materials -Reply
Tesla List wrote:
> Original Poster: ROBERT CRESSLER <59CREROB-at-menasha-dot-com>
> ...... using paper to absorb oil between dielectrics .... mmmh, could
> you use a material like gore-tex --- some type of expanded teflon --to act
> as both the dielectric and oil resevoir?
> ....thin plastics sheet and film source: www.pennfibre-dot-com
Possibly, but you would need to reduce the operating voltage versus a
cap made from polymer film, since the dielectric strength of a porous
material will be limited to the strength of the dielectric fluid. The
breakdown strength of dielectric fluids is always significantly less
than for a comparable thickness of non-porous polymer such as PP or PE.
A significant advantage of a multilayered dielectric, such as the
oil-kraft paper-polymer system, is that the oil-soaked paper layer has a
significantly higher "blended" dielectric constant than the polymer
layer, and is physically thinner than the polymer layer(s). This means
that the dielectric stess (in volts/mil) developed across the paper-oil
layer is, by design, significantly less than that across the polymer
layer. This approach places maximum stress on the component which can
withstand it best (the PP/PE layer), while allowing the paper layer to
perform the critical function of physically wicking dielectric oil
betwen the sheets to eliminate entrapped air. This benefit is lost in a
single oil and porous-dielectric system.
-- Bert --